Current-limiting device for low-voltage electrical power systems

ABSTRACT

A current-limiting device is formed as a self-contained electrical component having terminals which may be identical to fuse terminals to allow the interchangeable connection of the device in a low-voltage circuit with a current-limiting or conventional fuse. The device is formed of a plurality of contacts which engage the opposite edges of a spirally wound coil, with the contacts sequentially opening to gradually insert the turns of the spirally wound winding in series with the circuit in which the device is connected. A magnetic core surrounds the windings in order to increase the inductance of the coil.

United States Patent 1 Clausing CURRENT-LIMITING DEVICE FOR LOW-VOLTAGEELECTRICAL POWER SYSTEMS [75] Inventor:

[73] Assignee: l-T-E Imperial Corporation, Spring House, Pa.

[22] Filed: Sept. 13, 1974 [2|] Appl. No: 505,792

Related U.S. Application Data [63] Continuation-impart of Scr. No. 39()064 Aug. 20,

I973, Pat. No. 1836319.

Challis l. Clausing, Marlton, NJ.

[52] U.S. Cl 335/41; 317/11 C; 335/14;

335/[6 [5| lnt. CL- HOlH 77/06 [58] Field of Search 335/41, ll, l6, l4;

[56] References Cited UNITED STATES PATENTS Hayncs 335/41 1 Sept. 16,1975 3.8363) 9/1974 Clausing 317/11 C Primary Examiner-Harold BroomeAttorney Agent, or FirmOstr0lenk Faber Gerh & Soffcn [57] ABSTRACT AcurrentJimiting device is formed as a self-contained electricalcomponent having terminals which may be identical to fuse terminals toallow the interchangeable connection of the device in a low-voltagecircuit with a current-limiting or conventional fusew The dcvice isformed of a plurality of contacts which engage the opposite edges of aspirally wound coil with the contacts sequentially opening to graduallyinsert the turns of the spirally wound winding in series with thecircuit in which the device is connected. A magnetic core surrounds thewindings in order to increase the inductance of the coil.

25 Claims, 14 Drawing Figures PATENTEU SEP 1 8 975 SHEET 1 BF 9 a q W WW W W W W W W W m r w 4 .n I w W -wwWm/W F.\\\\\\\\\\\\\\\\ PATENTED SEPI 6 I975 SHEET 3 OF 9 W MI HN WHEN [H] SEP I 6 9. 5..

SHEET 5 OF 9 \Nm MNN ww PMEN'IEU 1 61975 sum 6 BF 9 t I g NNN I I LPATENIED I 6 5 SHEET 7 OF 9 NN E MWN CURRENT-LIMITING DEVICE FORLOVV-VOLTAGE ELECTRICAL POWER SYSTEMS RELATED APPLICATIONS Thisapplication is a continuation-in part application of my copendingapplication Ser. No. 390,064, filed Aug. 20, I973, now US. Pat. No.3,836,819 entitled Current Limiting Circuit Interrupter Device andassigned to the assignee of the present invention now US. Pat. No.3,836,819.

BACKGROUND OF THE INVENTION This invention relates to current-limitingdevices, and more specifically relates to a novel current-limitingcircuit component which is interchangeable with a fuse device and whichmay contain inductance increasing core means to increase the inductanceof the winding which is inserted into a circuit in order to limit thefault current in the circuit.

Currentlimiting devices are well known to those skilled in the art andfrequently take the form of current-limiting fuses or the like whichtend to substantially increase circuit impedance over the range of theiroperation. Such current-limiting fuses are frequently used incombination with circuit breakers so that the fuse will tend tosubstantially limit the magnitude of fault current if the short circuitwould exceed breaker rating. The circuit breaker interrupts relativelylow currents up to its rating and the fuse clears fault currents whichcould have been supplied from the circuit being protected above thebreaker rating. Other arrangements are well known for limiting the faultcurrent in a circuit in which impedance. and particularly resistance. issequentially introduced into the circuit as a circuit interrupter isoperated.

My above-noted copending application discloses a particularcurrent-limiting device which consists of an electrical winding having aplurality of turns. The winding is connected in series with a circuit tobe protected. The individual turns of the winding are normallyshortcircuited by individual contact elements bearing on opposite sidesof the individual turns or groups of turns of the winding. Theseindividual contacts are then springbiased into engagement with theirrespective turn. and are arranged to blow-of due to the magnetic fieldof a fault current which may be produced in this circuit. When thesecontacts blow off. the individual turn which they cooperate with isinserted into the power circuit. thereby to insert an inductiveimpedance in the circuit.

The various contacts may be further arranged so that they aresequentially forced out of engagement with their respective coils. sothat the full impedance of the entire winding is relatively graduallyinserted into the circuit.

The current through the circuit may then be limited either until itreturns to some normal value. or the limited current can be interruptedby a conventional interrupter in series with the circuit. As pointed outpreviously. the current will be limited to a value within the rating ofthis main interrupter device. Once the current has returned to itsnormal value or has been interrupted by the main interrupter device. theindividual contacts bearing on the turns off the helical coil can bereclosed by releasing latches which latch the contacts open when theyreach an opened position.

BRIEF DESCRIPTION OF THE PRESENT INVENTION In accordance with thepresent invention, a particular configuration is provided for the coilin which a spirally wound winding is supported within an insulationsupport and wherein the contacts are supported on opposite sides of thewinding by flanges extending from input terminals. The input terminalsthen have end regions which can permit the connection of the selfcontained device in a location which can also receive a conventionalfuse. Thus, the entire self-contained current-limiting device of theinvention becomes interchangeable with fuses which can be connected inpreexisting equipment or any equipment which is to be manufactured inthe future, with the ability to be used with either fuses or with thedevice of the invention.

The present invention further provides a novel con figuration for theoperating contacts which gradually insert portions of the winding intothe circuit being protected, and is further provided with a magneticcore for the winding in order to increase the winding inductance.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I schematically illustrates thepresent invention where the current-limiting impedance is a helicalwindmg.

FIG. 2 is a side view. partially in cross-section. of a circuit breakerequipped with the novel currentlimiting device of the invention. whereinthe impedance takes the form of a helical winding.

FIG. 3 is a cross-sectional view of FIG. 2 taken across the section line3-3 in FIG. 2.

FIG. 4 is a plan view of the top of the circuit breaker of FIG. 2.

FIG. 5 shows a modified arrangement for the mounting of a contactfinger.

FIG. 6 is a side view of a further embodiment of the invention whereinthe coil is spirally wound as contrasted to the helically wound coil ofFIGS. 2. 3 and 4.

FIG. 7 is an end view of the coil of FIG. 6.

FIG. 8 is a cross-sectional view through section line 8-8 of FIG. 7which illustrates the inter-connection be tween the contact elements ofthe spiral coil.

FIG. 9 is a perspective diagram of the spirally wound coil used in thecurrent limiter of the present invention. and schematically illustratesthe placement of the contacts and of a magnetic core which is used toincrease the inductance of the windings.

FIG. I0 is a front plan view of a completely selfcontained device whichuses the concepts schematically illustrated in FIG. 9.

FIG. II is a top view of FIG. I0.

FIG. I2 is a front view of FIG. II.

FIG. 13 is an enlarged view of the small section 13-13 in FIG. 12.

FIG. I4 is a cross-sectional view of FIG. 12 taken across the sectionline 14-14 in FIG. I2.

DETAILED DESCRIPTION OF THE DRAWINGS FIG. I schematically illustratesthe circuit of the present invention. and shows one phase of a powercircuit having input and output terminals I0 and II, respectively.wherein a circuit breaker 12, which may be of any conventional type, isconnected in series with terminals and 11 and is provided with aconventional operating mechanism.

The current-limiting device of the invention is shown as device 14 andconsists of a multi-turn winding 15 connected in series with the mainpower circuit. The input side of the circuit has a conductive support I6which supports a plurality of moving contacts 17 to 21 which, as will beseen later, are spring-loaded into en gagement with individual turns atlocations which are physically on the same side of the coil IS. Theoutput of the device [4 contains similar contact fingers 22 to 26,supported from conductive support [6a, which are in engagement withindividual coil turns on the opposite side of coil 15 from the sidewhich receives contact The normal current flow in the circuit of FIG. Iwill then be from terminal [0 through interrupter 12, through all ofinput fingers l7 to 21 and then through all of the output fingers 22 to26 of the terminal ll. The current flow from contacts 17 to 21 tocontacts 22 to 26 for a given coil turn will be in one direction overthe top of the turn and the opposite direction through the bottom of theturn. Thus, the entire winding 15 is, in effect, split up into parallelconductors with no current flowing around the coil as in an inductivedevice. Thus,

the coil 15 has no intentional impedance. The various contact fingers 17to 26 are then arranged. as will be later seen, to be blown off by thecurrent flow through the sections of the coil. Note, however, that anyother desired operating mechanism can be provided to operate theindividual contact fingers I7 to 26. If the blowoff mode is used when ashort-circuit occurs. the contact fingers 17 to 26 will blow off at somelevel determined by respective contact pressure springs. ()nce open,each finger may be held open by an individual latch. Note that the blowopen action will be cumulative in that. as soon as one finger blows off,more current must flow in the remaining parallel paths to force thesequential operation of each of the contact fingers 17 to 26. Thesprings may further be adjusted to ensure a particular sequence ofoperation such that contacts I7 through 2] blow off in sequence.contacts 22 through 26 blow off next in sequence. By properlycontrolling the number of turns and the geometry of coil 15, arcing atthe individual contact fingers can be eliminated, or minimized to apoint where the arc can be easily extinguished.

After the circuit has been operated and the circuit breaker I2 isopened. the contact fingers can be reset by spring pressure of theirbiasing springs when the individual latches of contacts 17 to 26 areremoved.

FIGS. 2, 3 and 4 schematically illustrate a conventional type of circuitinterrupter which has been modified to receive a currentlimiting deviceof the general type shown in FIG. 1. Referring first to FIG. 2, there isschematically illustrated a circuit breaker ofa generally conventionaltype and which has a molded support housing which carries tubularconductive terminals 41 and 42 which have tulip type disconnect contactassemblies 43 and 44 connected thereto by webs 45 and 46, respectively.The tulip type disconnect contacts 43 and 44 are then engageable withappropriate stationary conductors such as the stationary conductors 47and 48, respectively, which may be the stationary disconnect contactscontained in the interior of a conventional switchgear housing. Notethat the breaker shown in FIG. 2 is of the type that is conventionallyracked in and out of its switchgear cubicle. Conventional auxiliaryequipment is provided for the circuit breaker such as the currenttransformers 50 and 51 which encircle the lower terminal of the device.

The lower elongated terminal 41 is then connected to a movable contactarm which is pivotally mounted on stationary pivot 61 and which isoperated by rotation about pivot 61 by a conventional operating mechanisrn 62. Operating mechanism 62 is equivalent to mechanism 13 inFIG. 1. The movable contact 60 then cooperates with stationary contactelements, such as contact fingers disposed beneath contact springs 63 to66 and by an arcing contact 67. These various contact elements makesliding contact with contact arm 60 to complete a current path to thestationary conductive member 68.

All of the foregoing structure described in connection with FIGS. 2 and4 is of any desired conventional type and is simply intended to show acircuit breaker which can be of the type schematically shown for thecircuit interrupter 12 of FIG. 1.

In accordance with the invention, the current conducting member 68 ofFIG. 2 is connected as by brazing or bolting, or the like, to theterminal 70 of the multi-helica] winding 71.

The helical winding 71 of FIG. 2 is also shown in FIGS. 3 and 4 alongwith its input conductor 70. It will be seen from FIGS. 3 and 4 that thewinding 71 is a tenturn winding and has an output conductor 72 which isappropriately connected as by bolting or brazing, or the like, to theconductive support 42 of the circuit breaker.

The conductive member 68 of the circuit breaker of FIG. 2 has anelongated conductive plate member 80. shown in FIGS. 2, 3 and 4, whichserves as a support for a plurality of contact fingers to 99 which. ascan be best seen from FlG. 2, are pivotally mounted on a pivotal shaftconnected with contact finger 90.

Note that the pivot I00 can be a common pivot for each of contactfingers 90 to 99 or, alternatively, each contact finger can have its ownpivotal support cooperating with an extending support finger ofconductive body 80. Note further that the pivotal connection between themember 80 and the fingers 90 to 99 is a current carrying connectionwhich can be conventionally ac hievcd in any desired manner as byconductive washers and the like. Thus. in FIG. 4 and for the case ofcontact finger 91 there is shown a silver washer 9Iu which makes goodelectrical connection between the finger 9l and the extending comb-likerecess of elongated conductive plate 80. A belleville type washer 91bpresses finger 91 against the washer 91a.

It will be noted that each of the fingers 90 through 99 is arranged toengage the lateral side of each respective turn of the coil 71.Moreover, each of the contact fingers is provided with a biasing spring,such as the biasing spring 110, shown for finger 90, where the spring 0is carried on bracket 111. A similar compression spring is provided foreach of the contact fingers 91 through 99 as schematically illustratedin FIG. 3, where these springs are supported from the block 68.

The bottom of contact fingers 90 through 99 are then provided with latchrollers, such as the latch roller 120, shown in FIG. 2 for finger 90,where the latch roller cooperates with pivotally mounted latch 121 whichis pivoted on a fixed support shaft 122. Latch I2! is further providedwith a tension spring I23 which tends to normally rotate the latchclockwise and into engagement with a reset bar and stop member 124.Thus, the bar 124, which is movable from the position shown and to theleft and in the direction of arrow 125 of FIG. 2, may be a single barwhich operates all of the latches similar to latch 121, which cooperatewith the fingers 91 to 99.

It can now be understood that when the latch 121 and the other similarlatches are in the position shown, that the spring 110 and finger 90along with the other contact fingers will be pressed into engagementwith the respective turns of windings 71. Note, however, that if thecontact fingers 90 to 99 are operated to an open position by rotation ina clockwise direction about pivot 100, that the latches such as latch121 will rotate clockwise to the stop position defined by bar 124 inorder to latch the individual latch rollers, such as roller 120 of FIG.2.

A substantially identical contact finger configuration is provided onthe opposite side of winding 71 and is shown in FIG. 3 by the contactfingers 130 to 139. These contact fingers are mounted and biased andlatched in a manner substantially identical to that described above inconnection with fingers 90 to 99. Thus, the fingers are pivotallymounted on pivots such as pivot 140 which are current carrying pivots,and are spring biased into engagement with each of the turns of the coilby biasing springs, such as the biasing spring 141 carried from bracket142 carried on member 42.

Latches such as latch 143 are similarly provided to latch the latchrollers, such as latch roller 144 of the contact fingers 130 to 139,where the latch 143 and similar latches are biased counterclockwiseabout their support pivots, such as pivot 145 by tension springs 146. Areset stop bar 147 is also provided which is movable in the direction ofarrow 148 in order to allow reset of the individual contact fingers 130to 139 under the influence of their biasing springs, such as spring 141.

The current-limiting device shown in FIGS. 2 and 3 is operated inresponse to the current flow through the individual contact fingers 90through 99 and 130 through 139, where these fingers are opened due tothe magnetic blow-off effect of the current. Thus, the nor mal currentpath through the entire assemblage of FIGS. 2 and 3 will be fromterminal 47 through conductor 41, movable contact 60, stationary contactelements 63, 64, 65. 66 and 67, into the conductive members 68 and 80and then into the parallel conductive fingers 90 through 99 and then inparallel through the individual turns of coil 71. The parallel flowingcurrents exit through the parallel fingers 130 and 139 and into terminal42 and then terminal 48. The current path across the coil 71 is suchthat the current divides above and below the coil to flow in parallelaround the upper and lower half loops formed by the turns of the coil.

The current flow, for example, through finger 90 will then be upwardlyand then changing to the left to enter the right-hand side of the turnof coil 71 which is engaged by contact 90. This change in currentdirection then forms a blowoff path which creates a force which wouldtend to rotate the contact finger 90 (as well as fingers 91 to 99) in aclockwise direction and in opposition to the biasing force spring 110.Under normal current conditions. the biasing force of spring 110 issufficiently high to maintain good pressure contact but, when thecurrent increases, as due to a short circuit in the circuit beingprotected by the device, the magnetic forces created are sufficientlystrong to rotate fingers to 99 to an open position, where they arelatched by their respective latches, such as latch 12]. A similarblow-ofi path is formed for each of contacts 130 to 139, so that theytoo will be blown off when the current carried through these contactfingers becomes sufficiently high.

Preferably, the biasing springs, such as biasing springs and 141, are soarranged that the fingers blow off in a sequential manner. Thus, thebiasing forces can be so arranged that contact finger 90 will be thefirst to open when a predetermined current magnitude appears. Thenfingers 91 through 99 will blow off in sequence. This will then insertthe first turn of the inductive winding 71 into the circuit to cause arelatively small inductive impedance to appear in the circuit which willtend to limit current. At the same time, an increased current will flowinto the remaining closed fingers so that the next fingers will open,such contact fingers through 139 in sequence. thereby to insertsuccessive turns into the circuit which is being protected. Ultimately,each of the contact fingers will be opened so that the full coil 71 isinserted in series with the circuit being protected in order to limitthe current flow in the circuit.

FIG. 5 shows an alternate arrangement for mounting and latching thecontact fingers and is shown in connection with contact finger 90. Thus,in FIG. 5 an angle member is secured to plate 80 or may be otherwisesecured, for example, to the support molding 40 and carries the shaft122 which pivotally mounts the various latches, such as latch 12].

The biasing spring 123 for latch 121 is shown in FIG. 5 as a compressionspring which is seated at one end on the bracket 161 and at its otherend on the interior surface of latch 121, thereby to bias latch 121 in aclockwise direction and against stop bar 124. Clearly, other supportarrangements could be provided for supporting and biasing the latchessuch as latch 121.

The novel invention has been described above in connection with ahelically wound inductance coil where current flow through the coil fromthe contact fingers is along the winding length. FIGS. 6 to 8schematically illustrate a further embodiment of the invention inconnection with a spirally wound coil where current flow between thecontact elements is perpendicular to the length of the winding, with thecontacts engaging the winding at its end surfaces rather than itslateral surfaces as in FIGS. 2, 3 and 4.

Thus, in FIGS. 6, 7 and 8 there is shown a two-turn spiral winding whichhas terminal ends 171 and 172 (FIG. 7).

As best shown in FIGS. 6 and 8, contact means in cluding contact pairs173174, 175-176, 177-178 and 179-180 are electrically connected to andsupported by conductive members 181 and 182. Terminal 172 iselectrically and mechanically connected to conductive member 182 whileterminal 171 is electrically and mechanically connected to conductivemember 181. Thus, the terminals of coil 170 are connected so that thecoil is in series between conductive members 181 and 182 which are, inturn, appropriately connected to a circuit interrupting device as in thecase of FIGS. 2. 3 and 4. The individual contact members 173 to are thenarranged in a manner similar to that described, for example, inconnection with FIGS. 3, 4 and 5 where, for example, the contacts areassociated with appropriate biasing springs and latches, and the like.

During operation, the individual contact elements engage the ends ofrespective coil portions so that the electrical winding is simply aconductive shunt between the conductive members 181 and 182. However,when the electrical contacts 173 to 180 open, the inductance of the coil170 is inserted in series with conductive members 181 and 182 tointroduce impedance into a circuit which could, in turn, limit currentrise in the cireuit.

Referring next to FIGS. 9 to 14, there is disclosed therin theadditional subject matter of this continuation-inpart application.Referring first to FIG. 9. there is schematically illustrated a spirallywound coil 200 similar to the spirally wound arrangement of the embodiment of FIGS. 6, 7 and 8, where the spirally wound coil 200 contains2% turns for illustrative purposes only. Each side of the spirally woundcoil 200 then receives opposing contacts, shown as contacts 201 to 206on one side and opposing contacts 207 to 212, respectively, opposingcontacts 201 to 206 on the opposite side of the spiral winding 200. Eachof contacts 201 to 206 are then connected to one another and are connected to a first terminal 220 and, similarly, contacts 207 to 212 areconnected to one another and to a second terminal 221. The inside end ofcoil 220 is connected to terminal 220 and the outside end of coil 200 isconnected to terminal 221.

As will be later disclosed, the contacts 201 through 212 are providedwith suitable adjustable biasing springs. such that the contacts willblow open in a sequence which preferably introduces the inductance ofwinding 200 one-half turn at a time. Thus, under normal current-carryingconditions, all of contacts 201 to 212 engage opposite sides of spiral200 so that no induetance is interposed between terminals 220 and 221.However, upon the occurrence of a fault current. the contacts 201 to 212will open in the sequence: 201, 202, 203, 204, 205. 206, 210. 208,211,209, 212 and 207. The above sequence of operation permits thegradual insertion of the inductance of the coil 200 into the circuit toavoid the high induced voltages in the circuit and across the device.

An importance feature of FIG. 9 is that a magnetic core 230 can beformed around the winding in order to increase the inductance of thewinding. Note that the magnetic core can be formed of conventional steellaminations or the like.

FIGS. 10 to 14 illustrate the manner in which the device of FIG. 9 canbe manufactured to form a com pletely self-contained unit which isinterchangeable and replaceable with standard fuse-type devices.Referring now to FIGS. 10, 11 and 12, the self-contained device hasextending terminal bus members 240 and 241 which may have terminalopenings fixed on the same spacing as the terminal opening of aconventional highcurrent fuse which can be replaced by the conventionalnovel current-limiting device.

Each of busbars 240 and 241 are bolted to conductive angle members242-243 and 244-245, respectively, by bolts such as bolts 246 and 247.The entire assembly is then supported between the flanges 242 and 245.Each of the flanges or angles 242 to 245 are supported relative to oneanother by suitable insulation spacers best seen in FIG. 11 as typicalinsulation spacers 250 and 251 which are fixed to the various angles bybolts 252-253 and 254-255, respectively. Similar sets of spacers aredisposed below spacers 250 and 251 such spacers 256 and 260 in the viewof FIG. 14. Nuts 261 and 262 are shown in FIG. 10 for the spacers 256and 260, respectively (FIG. 14).

Spacers 251, 253, 256 and 260 receive an insulation plate 270 (FIGS. 11,12 and 14) which in turn receives the multi-turn spiral winding 271which is rigidly clamped into a central opening in the insulation plate270. One end of spirally wound winding 271 has a terminal portion 272(FIGS. 11 and 12) which is connected to the conductive angle 243 by thebolt connector 273. The opposite end of winding 271 and the interior endin the spiral winding is provided with an extension 275 (FIG. 11) whichis connected to the conductive angle 245 by bolts 276 and 277 (FIGS. 10and 11 Thus, the spiral winding 271 is connected in series betweeninsulated terminals 240 and 241.

The winding is further surrounded by transformer steel lamination packs280 and 281 which are supported by suitable angle supports shown asangle supports 282-283 and 284-285 for lamination packs 280 and 281,respectively. The transformer iron laminations increase the inductanceof the spiral winding 271 as desired.

Four packages of contact finger assemblies are then disposed within theself-contained device to make engagement and disengagement betweenangles 242 and 243 and the left-hand side of winding 271, and angles 244and 245 and the right-hand side of winding 271 in FIG. 1 1. Thus,contact assembly packages 290 and 291 are bolted to angles 242 and 243respectively while contact packages 293 and 294 are connected to angles244 and 245 respectively.

FIG. 10 shows bolts 295 to 298 which serve to hold contact package 293in position and further shows bolts 299 to 302 which serve to hold thepackage 294 in position. Similar bolts, such as bolts 306 and 307 (FIG.11) secure package 290 (FIG. 12) in position. Another similararrangement of bolts (not shown) holds package 291 in position.

Each of the individual packages of contacts 290 to 293 are identical inconstruction and are shown in detail in FIG. 13 in connection withpackage 294. Each package contains a plurality of pivotally movablecontact fingers shown in FIGS. 12 and 13 as contact fingers 310 to 313which are each pivotally mounted on a pivot pin 314. The pivot pin 314is carried from sta tionary conductive plates 315 to 319 which extendfrom a common conductive rear surface 320 (FIG. 12) whereby the plates315 to 319 serve as the teeth of a comb-shaped arrangement having thespine 320. The same comb-teeth plates 315 to 319 also support a secondpivot pin 321 which carries individual latch members 322 to 325 whichrespectively act to latch contact fingers 310 to 313 as will be laterdescribed.

Each of the contact fingers 310 to 313 have an extending region forreceiving a respective biasing spring. such as the biasing spring 330 inFIG. 12 for finger 310 and spring 331 in FIG. 14 for finger 313. Each ofthe contact fingers will obviously have a spring such as springs 330 and331 which tend to bias the contact strongly counterclockwise in FIG. 12and into engagement with the edge of a respective winding portion whichserves as a stationary contact of the winding 271. Note that FIG. 12shows the contact finger 310 in its opened position.

The latch members 322 to 325 are similarly provided with biasingsprings. such as biasing spring 340 in FIG. [2 for latch 322 where thespring 340 extends to the corresponding latch 341 in package 290. Thus.each of latches 322 to 325 are biased in a clockwise direction with thelatch stopping against the underside of the contact finger to thelatching position shown which latches the corresponding contact fingersopen once the contact fingers have been moved to their open position itwill be noted in FIG. 14 that the biasing spring 340 for latch 322 andsimilar springs 350. 351 and 352 for latches 323. 324 and 325 are alsoshown.

In order to close the contacts. means (not shown I are provided forrotating latches 322 to 325 in a counter clockwise position. therebypermitting the contact firlgers 3") to 313 to move counterclockwiseunder the influence of their biasing springs such as spring 330.

In order to obtain the desired sequential operation of the contacts.their individual contact spring forces are easily adjustable from aregion external of the device. with each ofthe springs. such as spring330. being supported from a bracket 360 (FIGS. 10 and 12) which has awindow 361 which exposes the adjustment screws 362 to 365 for each ofthe contact springs of the pack age. Similar windows. such as window370. are pro idcd for each of the other packages in the various angles.

ln operating the device of FIGS. 10 to 14. it will be noted that ablowoff current carrying path is formed from each terminal through eachcontact and into the spiral winding 27]. Thus. when current through thedevice exceeds a given value. the contact will tend to be moved bymagnetic forces to a disengaged position. By appropriately controllingthe biasing force of springs 336 for each of the contacts. and becauseeach contact will carry an increasing current after a preceding contacthas opened. the contacts can be arranged to open sequentially. therebyto insert the inductance of winding 27] one-half turn at a time with thecontacts latching open once they reach their fully open position. Thecurrenbcarrying device may then be restored to service by releasing eachof the latches of the contact fingers so that winding 271 will in effectbe short circuited by the current path through opposing contact fingersof the opposing packages 290-293 and 291-294.

Although the present invention has been described in connection withpreferred embodiments thereof. many other variations and modificationswill now become ap parent to those skilled in the art. It is preferred.therefore. that the present invention be limited not by the specificdisclosure herein. but only by the appended claims.

The embodiments of the invention in which an exclu sive privilege orproperty is claimed are defined as follows.

l. A sclt contained current-limiting device compris ing in combination:

a winding having a plurality of insulated turns and having first andsecond ends;

a first and second plurality of contacts connected to said first andsecond ends respectively. and movable into and out of engagement withrespective se lected regions of said plurality of insulated turns;

first and second extending terminals for said device;

said first plurality of contacts connected to said first terminal; saidsecond plurality of contacts con nected to said second terminal;

biasing means for biasing each contact of said first and secondplurality of contacts into engagement with said selected regions of saidturns. whereby a current path is formed essentially laterally throughsaid plurality of turns. whereby the inductance of said plurality ofturns is not connected between said first and second terminals;

operating means for moving at least selected contacts of said first andsecond plurality of contacts to a disengaged position relative to saidselected regions when the current flow between said first and secondterminals exceeds a predetermined value; and

latch means for latching said contacts in a disengaged position aftertheir movement thereto.

2. The device of claim 1 wherein said first and second terminals aregenerally coaxial with one another and are spaced from one another by agiven dimension. whereby said device is interchangeable with apreexisting fuse device.

3. The device of claim 1 wherein said operating means at least includesthe magnetic field produced by the current flow through said pluralityof contacts. whereby said current path applies a blow-off magnetic forcefor said contacts.

4. The device of claim 2 wherein said first and second terminals eachcomprise rectangular has members hav ing terminal openings therein.

5. The device of claim 4 wherein said plurality of first and secondcontacts. said biasing means. said winding. and said latch means arephysically supported from said first and second terminals.

6. The device of claim 5 wherein said first plurality of contacts arefixed to said first terminal. and wherein said second plurality ofcontacts are fixed to said second terminal. and which further includesinsulation spacer means for physically connecting said first and secondterminals to one another and for physically supporting said winding.

7. The device of claim I wherein said winding is spirally wound andwherein said first and second pluralities of contacts engage respectiveopposite sides of said winding.

8. The device of claim 7 wherein said first plurality of contacts arefixed to said first terminal, and wherein said second plurality ofcontacts are fixed to said second terminal. and which further includesinsulation spacer means for physically connecting said first and secondterminals to one another and for physically supporting said winding.

9. The device of claim 1 wherein each of said plurali ties of contactsconsist of identical assemblies of identical contacts.

10. The device of claim 8 wherein each of said pluralities of contactsconsist of identical assemblies of identical contacts.

1], The device of claim 1 which further includes magnetic core meansmounted on said winding and magnetically coupled thereto. thereby toincrease the inductance of each of said turns.

12. The device of claim 8 which further includes magnetic core meansmounted on said winding and magnetically coupled thereto. thereby toincrease the inductance of each of said turns.

13. A current-limiting device comprising, in combination:

a winding having a plurality of insulated turns;

a first and second plurality of contacts movable into and out ofengagement with respective selected regions of said plurality ofinsulated turns;

first and second terminals for said device;

said first plurality of contacts connected to said first terminal; saidsecond plurality of contacts con nected to said second terminal;

biasing means for biasing each contact of said first and secondplurality of contacts into engagement with said selected regions of saidturns, whereby a current path is formed essentially laterally throughsaid plurality of turns, whereby the inductance of said plurality ofturns is not connected between said first and second terminals;

operating means for moving at least selected contacts of said first andsecond plurality of contacts to a disengaged position relative to saidselected regions when the current flow between said first and secondterminals exceeds a predetermined value;

and magnetic core means mounted on said winding and magnetically coupledthereto, thereby to increase the inductance of each of said turns.

[4. The device of claim 13 wherein said winding is spirally wound andwherein said first and second pluralities of contacts engage respectiveopposite sides of said winding.

15. A current-limiting device comprising in combination:

a winding having a plurality of insulated turns;

a first and second plurality of contacts movable into and out ofengagement with respective selected regions of said plurality ofinsulated turns;

first and second insulated terminals for said device;

said first plurality of contacts connected to said first terminal; saidsecond plurality of contacts connected to said second terminal;

biasing means for biasing each contact of said first and secondplurality of contacts into engagement with said selected regions of saidturns. whereby a current path is formed essentially laterally throughsaid plurality of turns, whereby the inductance of said plurality ofturns is not connected between said first and second terminals;

operating means for moving at least selected contacts of said first andsecond plurality of contacts to a disengaged position relative to saidselected regions when the current flow between said first and (allsecond terminals exceeds a predctemiined value;

said winding being spirally wound; said first and second pluralities ofcontacts engaging opposite sides of said winding.

16. The device of claim 15 wherein each of said pluralities of contactsconsist of identical assemblies of identical contacts.

17. The device of claim 14 which further includes latch means forlatching said contacts in a disengaged position after their movementthereto.

18. The device of claim 15 which further includes latch means forlatching said contacts in a disengaged position after their movementthereto.

19. The device of claim 1 wherein said operating means operates saidcontacts in a predetermined sequence, thereby to sequentially insert theturns of said winding in series between said first and second terminals.

20. The device of claim 19 wherein said operating means at leastincludes the magnetic field produced by the current flow through saidplurality of contacts, whereby said current path applies a blow-offmagnetic force for said contacts.

21. The device of claim 8 wherein said operating means operates saidcontacts in a predetermined sequencc. thereby to sequentially insert theturns of said winding in series between said first and second terminals.

22. The device of claim 10 wherein said operating means operates saidcontacts in a predetermined sequence, thereby to sequentially insert theturns of said winding in series between said first and second terminals.

23. The device of claim ll wherein said operating means operates saidcontacts in a predetermined se quence, thereby to sequentially insertthe turns of said winding in series between said first and secondterminals.

24. The device of claim 13 wherein said operating means operates saidcontacts in a predetermined sequence, thereby to sequentially insert theturns of said winding in series between said first and second terminals.

25. The device of claim 15 wherein said operating means operates saidcontacts in a predetermined sequence. thereby to sequentially insert theturns of said winding in series between said first and second terminalsi

1. A self-contained current-limiting device comprising in combination: awinding having a plurality of insulated turns and having first andsecond ends; a first and second plurality of contacts connected to saidfirst and second ends respectively, and movable into and out ofengagement with respective selected regions of said plurality ofinsulated turns; first and second extending terminals for said device;said first plurality of contacts connected to said first terminal; saidsecond plurality of contacts connected to said second terminal; biasingmeans for biasing each contact of said first and second plurality ofcontacts into engagement with said selected regions of said turns,whereby a current path is formed essentially laterally through saidplurality of turns, whereby the inductance of said plurality of turns isnot connected between said first and second terminals; operating meansfor moving at least selected contacts of said first and second pluralityof contacts to a disengaged position relative to said selected regionswhen the current flow between said first and second terminals exceeds apredetermined value; and latch means for latching said contacts in adisengaged position after their movement thereto.
 2. The device of claim1 wherein said first and second terminals are generally coaxial with oneanother and are spaced from one another by a given dimension, wherebysaid device is interchangeable with a pre-existing fuse device.
 3. Thedevice of claim 1 wherein said operating means at least includes themagnetic field produced by the current flow through said plurality ofcontacts, whereby said current path applies a blow-off magnetic forcefor said contacts.
 4. The device of claim 2 wherein said first andsecond terminals each comprise rectangular bus members having terminalopenings therein.
 5. The device of claim 4 wherein said plurality offirst and second contacts, said biasing means, said winding, and saidlatch means are physically supported from said first and secondterminals.
 6. The device of claim 5 wherein said first plurality ofcontacts are fixed to said first terminal, and wherein said secondplurality of contacts are fixed to said second terminal, and whichfurther includes insulation spacer means for physically connecting saidfirst and second terminals to one another and for physically supportingsaid winding.
 7. The device of claim 1 wherein said winding is spirallywound and wherein said first and second pluralities of contacts engagerespective opposite sides of said winding.
 8. The device of claim 7wherein said first plurality of contacts are fixed to said firstterminal, and wherein said second plurality of contacts are fixed tosaid second terminal, and which further includes insulation spacer meansfor physically connecting said first and second terminals to one anotherand for physically supporting said winding.
 9. The device of claim 1wherein each of said pluralities of contacts consist of identicalassemblies of identical contacts.
 10. The device of claim 8 wherein eachof said pluralities of contacts consist of identical assemblies ofidentical contacts.
 11. The device of claim 1 which further includesmagnetic core means mounted on said winding and magnetically coupledthereto, thereby to increase the inductance of each of said turns. 12.The device of claim 8 which further includes magnetic core means mountedon said winding and magnetically coupled thereto, thereby to increasethe inductance of each of said turns.
 13. A current-limiting devicecomprising, in combination: a winding having a plurality of insulatedturns; a first and second plurality of contacts movable into and out ofengagement with respective selected regions of said plurality ofinsulated turns; first and second terminals for said device; said firstplurality of contacts connected to said first terminal; said secondplurality of contacts connected to said second terminal; biasing meansfor biasing each contact of said first and second plurality of contactsinto engagement with said selected regions of said turns, whereby acurrent path is formed essentially laterally through said plurality ofturns, whereby the inductance of said plurality of turns is notconnected between said first and second terminals; operating means formoving at least selected contacts of said first and second plurality ofcontacts to a disengaged position relative to said selected regions whenthe current flow between said first and second terminals exceeds apredetermined value; and magnetic core means mounted on said winding andmagnetically coupled thereto, thereby to increase the inductance of eachof said turns.
 14. The device of claim 13 wherein said winding isspirally wound and wherein said first and second pluralities of contactsengagE respective opposite sides of said winding.
 15. A current-limitingdevice comprising in combination: a winding having a plurality ofinsulated turns; a first and second plurality of contacts movable intoand out of engagement with respective selected regions of said pluralityof insulated turns; first and second insulated terminals for saiddevice; said first plurality of contacts connected to said firstterminal; said second plurality of contacts connected to said secondterminal; biasing means for biasing each contact of said first andsecond plurality of contacts into engagement with said selected regionsof said turns, whereby a current path is formed essentially laterallythrough said plurality of turns, whereby the inductance of saidplurality of turns is not connected between said first and secondterminals; operating means for moving at least selected contacts of saidfirst and second plurality of contacts to a disengaged position relativeto said selected regions when the current flow between said first andsecond terminals exceeds a predetermined value; said winding beingspirally wound; said first and second pluralities of contacts engagingopposite sides of said winding.
 16. The device of claim 15 wherein eachof said pluralities of contacts consist of identical assemblies ofidentical contacts.
 17. The device of claim 14 which further includeslatch means for latching said contacts in a disengaged position aftertheir movement thereto.
 18. The device of claim 15 which furtherincludes latch means for latching said contacts in a disengaged positionafter their movement thereto.
 19. The device of claim 1 wherein saidoperating means operates said contacts in a predetermined sequence,thereby to sequentially insert the turns of said winding in seriesbetween said first and second terminals.
 20. The device of claim 19wherein said operating means at least includes the magnetic fieldproduced by the current flow through said plurality of contacts, wherebysaid current path applies a blow-off magnetic force for said contacts.21. The device of claim 8 wherein said operating means operates saidcontacts in a predetermined sequence, thereby to sequentially insert theturns of said winding in series between said first and second terminals.22. The device of claim 10 wherein said operating means operates saidcontacts in a predetermined sequence, thereby to sequentially insert theturns of said winding in series between said first and second terminals.23. The device of claim 11 wherein said operating means operates saidcontacts in a predetermined sequence, thereby to sequentially insert theturns of said winding in series between said first and second terminals.24. The device of claim 13 wherein said operating means operates saidcontacts in a predetermined sequence, thereby to sequentially insert theturns of said winding in series between said first and second terminals.25. The device of claim 15 wherein said operating means operates saidcontacts in a predetermined sequence, thereby to sequentially insert theturns of said winding in series between said first and second terminals.